A study has shown that Katy Perry's track 'Birthday' encourages people to become happy.

The US star released the song earlier this year as a single from her 2013 record 'Prism' and research has suggested that it promotes happy thoughts.

Spotify have teamed up with University of Groningen's neuroscience expert Jacob Jolij to examine how certain songs impact upon people's emotions.

He said: "Happy songs are up-tempo, have strong rhythm, positive lyrics, and are typically in a major key. The up-tempo rhythm of Katy Perry's 'Birthday' will encourage active movement, which is good for your mood. Furthermore some research suggests that the major key unconsciously reminds you of a falling pitch - a feature which in both human and animal vocalisations asserts dominance and confidence."

Jolij added: "Music that can help you to overcome fear needs to be slow, relaxing, but have major chords to evoke positive feelings and lyrics that deal with your negative thoughts, such as Coldplay's 'Magic'."

The expert meanwhile concluded that tunes like Avicii's 'Wake Me Up' provokes feelings of excitement.

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Watch the video for Katy Perry's 'Birthday' below: